…reads, vCache with time-based flushing consistently hit about 27000 per second, whereas without …at a more constant and, potentially, submaximal, rate compared to dirty-page-threshold flushing, …errors = 10 table_open_cache = 10240 max_allowed_packet = 16M binlog_cache_size = 16M max_heap_table_size =…
Post: What MySQL buffer cache hit rate should you target
June 29, 2006 By 5 Comments
…What cache hit rate is good for optimal MySQL Performance” is typical question I’… were these reads/writes, how good was OS or SAN cache hit rate – something you would not see otherwise. The bad luck is… reads”, “OS file writes” from SHOW INNODB STATUS for Innodb tables. In MySQL 5.0+ you can also use Innodb_data…
Post: Why you should ignore MySQL's key cache hit ratio
February 28, 2010 By 28 Comments
…cache interchangeably. However, I will be careful about the difference between “rate” and “ratio”. In this article, the key cache miss rate… to MyISAM tables. Consider your mixture …cache‘s creator and assume that misses are more expensive than hits, then you care about cache misses, not cache hits…
Post: MySQL Query Cache
July 27, 2006 By 70 Comments
… it will not be cached. Table level granularity in invalidation – If table gets modification all queries derived from this table are invalidated at once… queries as if query cache hit happens Com_select is not incremented. But if you have just 20% Cache hit rate does it mean it is not worth it ? Not really it depends on which queries are cached, as well…
Post: Beware large Query_Cache sizes
March 23, 2007 By 3 Comments
… with MySQL Query Cache being source of serious problems. One would see queries both for MyISAM and Innodb tables mysteriously stalling for few seconds with “NULL” in State column. These could be troubleshooted to waiting on Query Cache which… to happen more regularly but this also should affect query cache hit rate.
Comment: When should you store serialized objects in the database?
January 21, 2010 By 47 Comments
… aggregations on the index tables if you like. Or, you can aggregate in process in the background and cache the values. I… isn’t worth it if you have a lot of tables that you’re often modifying. Sure, this is purportedly fixed… will read and write through to cache without any extra effort. We see a 99.9% cache hit rate in production. In practice, that…
Post: Using flow control functions for performance monitoring queries
May 24, 2008 By 12 Comments
… web site performance analyzes. As you can see in this table we have recorded “wtime” which is wallclock time it took… cache (or be served from the cache all together). Bots however tend to visit distinct pages which tends to have significantly lower cache hit rate…
Comment: Shard-Query turbo charges Infobright community edition (ICE)
May 6, 2011 By 23 Comments
… would have compared. 3. Which indexes were present on the table, because the queries look like natural ones for very effective… shorter rows to improve cache hit rates. I tend to grimace when I see 100 character varchars in frequently queried tables without covering indexes. StateName VARCHAR(100) in a commonly queried table? A bad joke for anyone…
Post: MySQL 5.6 vs MySQL 5.5 and the Star Schema Benchmark
March 11, 2013 By 7 Comments
…reboot, when the FS cache is cold The remaining…RATE: 0 * PAGES_CREATE_RATE: 0 PAGES_WRITTEN_RATE: 0.032257023966968806 * PAGES_WRITTEN_RATE: 0 NUMBER_PAGES_GET: 6731790 * NUMBER_PAGES_GET: 6731253 HIT_RATE: 995 * HIT_RATE…WeekDayFl tinyint ); DROP TABLE IF EXISTS lineorder; CREATE TABLE IF NOT EXISTS…
Post: SHOW INNODB STATUS walk through
July 17, 2006 By 40 Comments
…tables for normal operation so number of tables locked normally stays 0, unless it is ALTER TABLE or similar statement, or if LOCK TABLES…done to OS cache, and being …hit ratio which measures buffer pool efficiency. 1000/1000 corresponds to 100% hit rate. It is hard to tell what buffer pool hit rate…
